Genetic Expression
The DNA (deoxyribonucleic acid) of which genes are made comprises both protein-encoding or "structural" genes and control regions that mediate the expression of their information through provision of sites for RNA polymerase binding, information for ribosomal binding sites, etc. Encoded protein is "expressed" from its corresponding DNA by a multistep process within an organism by which:
1. The enzyme RNA polymerase is activitated in the control region (hereafter the "promoter") and travels along the structural gene, transcribing its encoded information into messenger ribonucleic acid (mRNA) until transcription of translatable mRNA is ended at one or more "stop" codons.
2. The mRNA message is translated at the ribosomes into a protein for whose amino acid sequence the gene encodes, beginning at a translation "start" signal, most commonly ATG (which is transcribed "AUG" and translated "f-methionine").
In accordance with the genetic code, DNA specifies each amino acid by a triplet or "codon" of three adjacent nucleotides individually chosen from adenosine, thymidine, cytidine and guanine or, as used herein, A,T,C, or G. These appear in the coding strand or coding sequence of double-stranded ("duplex") DNA, whose remaining or "complementary" strand is formed of nucleotides ("bases") which hydrogen bond to their complements in the coding strand. A complements T, and C complements G. These and other subjects relating to the background of the invention are discussed at length in Benjamin Lewin, Gene Expression 1, 2 (1974) and 3 (1977), John Wiley and Sons, N.Y. This and the other publications alluded to herein are incorporated by reference.